spinal anaesthesia factor affecting.pptx
- 1. Factor effecting and complication of spinal anaesthesia Moderator – Dr. Jahanara(AP) Presentor -Dr. Manisha( Pg3) Dr.punit(pg2)
- 2. Baricity Density of a solution in relation to density of CSFdensity (density of CSF is 1.00059 g/mL) • Hypobaric solutions : raise against gravity • Isobaric solutions : tend to remain in the same sight where they are injected • Hyperbaric solutions : tend to follow gravity • Dextrose and sterile water are commonly added to local anesthetic solutions to make either hyperbaric or hypobaric, respectively
- 3. • The administration of hyperbaric local anesthetic to patients in the lateral decubitus position will result in a preferential anesthetic effect on the dependent side • whereas the opposite is true for the administration of a hypobaric solution.
- 4. Temperature effect • CSF and local anesthetic density change with temperature. Plain bupivacaine 0.5%, for example, may be isobaric at 24°C but is slightly hypobaric at 37. • increasing temperature decreases density of a solution and warming of local anesthetic solution to body temperature, • therefore making it more hypobaric, increases the block height in patients who remain seated for several minutes after injection.
- 5. • Patient characteristics 1.Age-Advanced age is associated with increased block height – In older patients, CSF volume decreases,whereas its specific gravity increases. Furthermore, the nerve roots appear more sensitive to local anesthetic in the aged population –2.Gender-sex can theoretically affect block height by several mechanisms. CSF density is higher in males, thereby reducing the baricity of local anesthetic solution and possibly limiting the extent of cephalad spread.
- 6. • CSF density can also vary between and within individuals depending on sex, menopausal status, and pregnancy • The density of CSF is lower in women compared with men, • premenopausal compared with postmenopausal patients, and • pregnant compared with nonpregnant people
- 7. • Height – within the range of “normal-sized” adults, patient height does not seem to affect the spread of spinal anesthesia. This is likely because the length of the lower limb bones rather than the vertebral column contributes most to adult height. • Weight - obese patients, and possible increased epidural fat, may decrease the. CSF volume and therefore increase the spread of local anesthetic and block height.
- 8. Effect of spinal anamolies • Scoliosis, An abnormal curvature of the spine in the coronal plane (sideways curvature) may not significantly impact the spread of hyperbaric solutions in the supine position, although it possibly makes insertion of the needle more difficult. • Kyphosis-abnormal curvature of the spine in the sagittal plane (forward rounding of the back) is more likely to affect the spread of hyperbaric solutions. The anteroposterior curves are crucial for the gravitational spread of the solution.
- 9. Lumbar lordosis- Changes in the normal lumbar curvature (lordosis), such as in pregnancy, can also influence spread. Flexing the hip joint can flatten the lumbar lordosis and reduce cephalad (towards the head) spread of the anesthetic.
- 10. Position of patient • Intrathecal local anesthetic appears to stop spreading 20to 25 minutes after injection, thus positioning of the patient is most important during this time period, • but particularly in the initial few minutes. However, marked changes in patient posture up to two hours after injection can still result in significant changes in the block level, probably because of bulk movement of CSF.
- 11. • Although a 10-degree head-up tilt can reduce the spread of hyperbaric solutions without hemodynamic compromise • Flexion of the hips in combination with the Trendelenburg position flattens the lumbar lordosis and increases cephald spread of hyperbaric solutions. • A “saddle block” where only the sacral nerve roots are anesthetized can be achieved by using a small dose of hyperbaanesthetic while patient in the sitting position for up to 30 minutes
- 12. Procedural factors • Orientation of orifice of needle -With hypobaric, but not hyperbaric, solutions,cephalad alignment of the non-cutting needle orifice may produce greater spread. • By directing the needle orifice to one side, a more marked unilateral block can be achieved
- 13. • Level of injection- the difference is only one interspace more cephalad, the block height is greater when using isobaric bupivacaine. • Injection Rate: • Faster injection: May lead to a faster onset of the block and potentially a slightly higher sensory block height, especially with plain solutions.
- 14. Slower injection: • May allow for better control of the spread, particularly with larger volumes. Slow and careful injection of local anaesthetic is generally recommended to minimize the risk of sudden hypotension and to allow for proper distribution of the drug.
- 15. Barbotage: Mechanism: Barbotage involves repeatedly withdrawing and re- injecting cerebrospinal fluid (CSF) during the injection to create currents and disperse the local anesthetic. Potential effect: • It is thought to increase the spread and potentially the height of the block, but evidence is not conclusive.
- 16. Indirect effects of SA drugs Cardiovascular effects Due to sympathetic blockade there is vasodilatation of both resistance and capacitance vessels Fall in peripheral vascular resistance Posture dependent fall in cardiac output Fall in BP
- 17. Indirect effects of SA drugs Cardiovascular effects • Marey’s law :baroreceptors in the carotid sinus and the aortic arch normally respond to a fall in blood pressure by producing a compensatory tachycardia
- 18. Indirect effects of SA drugs Cardiovascular effect • Brain bridge reflex predominates during spinal anaesthesia : venous pooling in the periphery reduces stimulation of volume receptors - diminishes the action of cardiac sympathetic nerves- vagal preponderance - bradycardia • Oxygen consumption is reduced due to hypotension and muscle relaxation
- 19. Indirect effects of SA drugs Respiratory effects • High spinal may cause paralysis of intercostal nerves • Bronchodilatation secondary to hypotension or to reduced pulmonary blood volume
- 20. Indirect effects of SA drugs Gastro-intestinal effects • Contracted bowel and relaxed sphincters due to sympathetic blockade • In the absence of vagal block – increase in peristalsis and intraluminal pressure
- 21. Spinal anaesthesia in pregnancy Decreased dose requirement due to • Mechanical factor : compression of IVC causes shunting of blood to the venous plexus in the vertebral canal- decreased vertebral canal space and CSF volume • Hormonal factor – higher progesterone levels increase neuronal sensitivity
- 22. Complications 1. Immediate complications - Hypotension - Bradycardia and Cardiac arrest. - High and Total spinal block leading to respiratory arrest. - Urinary retention. - Epidural hematoma, Bleeding.
- 23. Complications 2. Late complications - Post dural puncture headache (PDPH) - Backache - Nausea - Focal neurological deficit - Bacterial meningitis - Sixth Cranial nerve palsy - Urinary retention
- 24. PDPH • Post-dural-puncture headache (PDPH) is a complication of puncture of the dura mater (one of the membranes around the brain and spinal cord). • The headache is severe and ivolving the back and front of the head and spreading to the neck and shoulders, sometimes involving neck stiffness.
- 25. Sign and symptoms • It is exacerbated by movement and sitting or standing and is relieved to some degree by lying down. Nausea, vomiting, pain in arms and legs, hearing loss, tinnitus, vertigo, dizziness and paraesthesia of the scalp are also common • .PDPH typically occurs hours to days after puncture and presents with symptoms such as headache (which is mostly bi-frontal or occipital)
- 33. How to prevent Delayed Complication • Use Thin Spinal needles • Sterile Precaution
- 34. It is widely considered that pencil-point needles (Whiteacre or Sprotte) make a smaller hole in the dura and are associated with a lower incidence of headache (1%) than conventional cutting-edged needles (Quincke)
- 35. Treatment of spinal headache Prolonged or severe headaches may be treated with • epidural blood patch performed by aseptically injecting 15-20ml of the patient's own blood into the epidural space. • This then clots and seals the hole and prevents further leakage of CSF.
- 36. High spinal Anaesthesia High spinal anesthesia is a complication of central neuraxial techniques that include spinal and epidural anesthesia It is defined as a spread of local anesthetic affecting the spinal nerves above T4 • The effects are of variable severity depending on the maximum level that is involved but can include cardiovascular and/or respiratory compromise
- 37. • In total spinal anesthesia, there is an intracranial spread of local anesthetic resulting in loss of consciousness • Contribiting factors: • Local anesthetic dose • Positioning of patient • Pre-existing epidural block • Unrecognized dural puncture and intrathecal injection • Accidental subdural block
- 39. Treatment of complications Hypotension is due to vasodilation and a functional decrease in the effective circulating volume. 1. Vasoconstrictor drugs 2. All hypotensive patients should be given OXYGEN by mask until the blood pressure is restored. 3. Raising their legs thus increasing the return of venous blood to the heart.
- 40. Treatment of complications 4. Increase the speed of the intravenous infusion to maximum until the blood pressure is restored to acceptable levels. 5. Treatment of bradycardia- give atropine intravenously.
- 41. Pregnancy & Spinal • Pre loading with IV Fluids • Left lateral Position • Vasopressors • Oxygen therapy
- 42. Thank you